A Cooperative SIP Infrastructure for Highly Reliable Telecommunication Services BY Sai kamal neeli AVINASH THOTA

Introduction  This paper talks about providing a solution for the communication networks which are vulnerable to various attacks (like DOS, eclipse attacks etc). Here the problem is approached by using a SIP server in its normal mode of operation and the user agents of the SIP server forms a P2P network among themselves

INTRODUCTION Major problems with VoIP which are unsolved are reliability, security, QoS, etc. Most of the users use the PSTN which is 100% reliable SIP: Basically known as session initiation protocol. SIP is a signaling protocol which is used in the application layer With SIP, application sessions are established and then we can modify them and finally we can terminate the session. P2P: Peer-to-Peer networks, these networks are mainly used for sharing the files

Cooperative SIP (CoSIP)  Overview Cooperative SIP architecture: CoSIP  It is a hybrid architecture that benefits from the advantages of both server-based and P2P-based SIP networks  SIP User Agents organize themselves into a P2P network  SIP infrastructure and SIP User Agents cooperate in order to provide the best service Improve reliability, survivability, security and lookup performance

How Reliability is Improved in SIP with CoSIP Here traditional method of P2P approach is not followed Here the SIP infrastructure has dedicated SIP servers. P2P network is formed additionally by the SIP user agents. P2P network provide high reliability and self-organization Local failures can be recovered automatically by neighboring peers Data is replicated on a set of nodes. Even large failures affect only a part of the network DoS attacks or network failure attacks are avoided by the DHT, this DHT is used as a backup. Therefore SIP server availability is improved

Implementation of CoSIP Prototype. Design: Here we are using CoSIP as local SIP proxy. Bamboo DHT is used, supporting better routing and improved maintenance. Super node approach is used, here the powerful peers are connected directly to the DTH and the week peers have a indirect connection to DTH

Message Processing: In the cooperative operation mode CoSIP proxy processes the SIP messages. New data structure is created when a Register message is sent by the user agent to the SIP server through the CoSIP proxy. Register message is modified by the CoSIP proxy and then forwarded to the SIP server. In establishing the session with the CoSIP, here when the INVITE message is forwarded to the SIP server by the proxy a message is received by the UAC (“100 Trying” message). This notifies the UAS about the processing of the request Here a modular approach is used for handling the sate machine of the CoSIP proxy.

Expected Results Reliability is improved with the use of the DHT. Bothe the DHT and the server work parallel. So if one fails other one can be used. CoSIP servers are more advanced than the traditional CA. Therefore better security is possible

Conclusion  CoSIP provides a low-cost solution for significantly improving the reliability of SIP networks  Implementation  CoSIP as an external proxy application  compatible to existing SIP networks  Cooperative (server + DHT) as well as DHT-only mode possible  CoSIP is a hybrid architecture which provides better reliability, survivability, security and performance simultaneously

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